FIX: ensure property key strings are serialized in correct order (map…

…box#93)

encode.js

@@ -2,7 +2,7 @@
 
 module.exports = encode;
 
-var keys, keysNum, dim, e,
+var keys, keysNum, keysArr, dim, e,
     maxPrecision = 1e6;
 
 var geometryTypes = {
@@ -17,6 +17,7 @@ var geometryTypes = {
 
 function encode(obj, pbf) {
     keys = {};
+    keysArr = [];
     keysNum = 0;
     dim = 0;
     e = 1;
@@ -26,8 +27,6 @@ function encode(obj, pbf) {
     e = Math.min(e, maxPrecision);
     var precision = Math.ceil(Math.log(e) / Math.LN10);
 
-    var keysArr = Object.keys(keys);
-
     for (var i = 0; i < keysArr.length; i++) pbf.writeStringField(1, keysArr[i]);
     if (dim !== 2) pbf.writeVarintField(2, dim);
     if (precision !== 6) pbf.writeVarintField(3, precision);
@@ -85,7 +84,10 @@ function analyzePoint(point) {
 }
 
 function saveKey(key) {
-    if (keys[key] === undefined) keys[key] = keysNum++;
+    if (keys[key] === undefined) {
+        keysArr.push(key);
+        keys[key] = keysNum++;
+    }
 }
 
 function writeFeatureCollection(obj, pbf) {

test/fixtures/issue90.json

@@ -0,0 +1,13 @@
+{
+  "type": "Feature",
+  "" : "",
+  "xyz" : null,
+  "!" : {},
+  "~" : [],
+  "2" : [null],
+  "properties": { "foo" : null, "" : null, "bar" : {} },
+  "geometry": {
+    "type": "Point",
+    "coordinates": [100.0, 0.0]
+  }
+}

test/validate.test.js

@@ -15,6 +15,7 @@ for (var name in geojsonFixtures) {
 test('roundtrip issue', roundtripTest(getJSON('issue62.json')));
 
 test('roundtrip custom properties', roundtripTest(getJSON('props.json')));
+test('roundtrip issue90', roundtripTest(getJSON('issue90.json')));
 test('roundtrip single-ring MultiPolygon', roundtripTest(getJSON('single-multipoly.json')));
 
 test('roundtrip valid closed polygon with high-precision coordinates', function (t) {